Witch of the following is closest to 27.8 x 9.6 is it 280, 2800, 300, or 3000

Mr and mrs smith buy tickets for themselves and their four children. the cost of an adult ticket is ? 6 more than the adult ticket. the total cost of the six tickets is ? 40.50 work out the cost of an adult ticket. in your working let c be the cost of the child ticket and a be the cost of the adult ticket.

What is the upper quartile in the box plot?

Math i have no idea how to do a and b